Researchers at Los Alamos National Laboratory have developed a new, patent-pending technology called the Integrated Composite Optical Neutron Sensor, or ICONS, that can accurately measure neutrons in both low and high radiation environments.
“Measuring neutrons accurately is critical for a variety of applications, including energy research, national security, scientific experiments, medicine and nuclear safeguards,” said Markus Hehlen, scientist at Los Alamos and ICONS team lead. “But getting accurate neutron measurements is surprisingly hard.”
One area that ICONS could significantly improve is counterproliferation science for nuclear security.
Neutrons provide a uniquely revealing signature that enables the detection of illicit nuclear activities, the precise characterization of radioactive materials and the reliable diagnostics and control of nuclear reactors. Neutrons are typically locked inside atoms, but in some nuclear processes, neutrons are released as free particles. These free neutrons are produced in nuclear fission, nuclear fusion and other radiation-related activities.
Most free neutrons encountered on Earth’s surface are produced when solar, galactic and extragalactic cosmic rays hit the air molecules in Earth’s atmosphere or in the plasma of lightning bolts. This natural background is roughly 10 neutrons per square foot per second. On the other hand, free neutrons produced by fission or fusion are rarer in nature and are often the result of human nuclear activities.
As a result, detecting neutron signatures is essential for modern nuclear security efforts, which is where ICONS could play an important role.
Neutron detectors must work across a wide range of conditions — sometimes, neutrons are rare and hard to spot. Other times they appear in extremely high numbers. On top of that, neutron signals are often buried in strong background radiation from gamma rays, which can confuse many detectors. To make matters more complicated, many existing neutron detectors rely on helium-3, a gas that has been in severe global shortage for more than 20 years. This shortage has limited access to neutron detection for commercial, academic and industrial users, and has raised the cost significantly.
To overcome these challenges, the team developed ICONS, a novel neutron detection technology that accurately measures neutrons in both low- and high-radiation environments, even when strong gamma radiation is present. ICONS responds very quickly, making it useful for measuring short neutron bursts or high-rate neutron sources in real time. ICONS also overcomes supply-chain constraints by using naturally abundant and commercially available lithium-6 rather than scarce helium-3.
A key advantage of ICONS is its wide and linear measurement range. It can detect anything from individual background neutrons up to extremely intense neutron fluxes without losing accuracy. This allows one system to replace multiple specialized detectors.
By making high-performance neutron detection more affordable and accessible, ICONS can support major societal needs: energy development (fusion and fission), nuclear safeguards and nonproliferation, worker radiation safety, scientific research, cancer therapy and even agricultural soil-moisture measurements. Early adopters are expected to include fusion-energy companies and research institutions that need reliable, flexible and future-proof neutron detection tools.
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